Sugar chain related enzymes (oligosaccharide-processing enzymes) such as glycosyltransferase and glycosidase are important classes of molecules involved in the synthesizing specific oligosaccharide structures on proteins (Kornfeld, R. et al. (1985), Ann. Rev. Biochem. 54, 631-664; and Brockhausen, I. et al. (1999), Biochim. Biophys. Acta 1473, 67-95) and sphingolipids (Butters, T. D. et al. (2000), Chem. Rev. 100. 4683-4696). The use of specific inhibitors of these enzymes enables the regulation of cellular functions, and thus these inhibitors are of interest. Enzymatic hydrolysis of a glycosidic bond generally takes place via general acid and base catalysts that require two critical residues (i.e., a proton donor and a nucleophile) (Sinnott, M. L. et al. (1990), Chem. Rev. 90, 1171-1202; Rye, C. S. et al. (2000), Curr. Opin. Chem. Biol. 4, 573-580; and Unligil, U. M. et al. (2000), Curr. Opin. Struct. Biol. 10, 510-517). A distorted half-chair-like transition state leading to a carboxonium ion is considered to be involved in the reaction (FIG. 1). Five-membered iminocyclitols carrying hydroxyl groups with specific orientation to mimic the shape and charge of the transition state of the reacting sugar moiety have been shown to be potent inhibitors of such enzymes (Winchester, B. et al. (1993), Biochem. J. 290, 743-749; Fleet, G. W. J. et al. (1985), Tetrahedron Lett. 26, 3127-3130; Liu, K. K.-C. et al. (1991), J. Org. Chem. 56, 6280-6289; Kato, A. et al. (1999), Carbohydr. Res. 316-95-103; Takebayashi, M. et al. (1999), J. Org. Chem. 64, 5280-5291; and Saotome, C. et al. (2000), Bioorg. Med. Chem. 8, 2249-2261). Since a cation-like transition state is expected to be involved in both the glycosyltransferase and glycosidase catalyzed reaction, five- and six-membered iminocyclitols can be used as core components for the development of transition-state analog inhibitors of both families of enzymes (Winchester, B. et al. (1993), Biochem. J. 290, 743-749; Fleet, G. W. J. et al. (1985), Tetrahedron Lett. 26, 3127-3130; Liu, K. K.-C. et al. (1991), J. Org. Chem. 56, 6280-6289; Kato, A. et al. (1999), Carbohydr. Res. 316-95-103; Takebayashi, M. et al. (1999), J. Org. Chem. 64, 5280-5291; Saotome, C. et al. (2000), Bioorg. Med. Chem. 8, 2249-2261; Kajimoto, T. et al. (1991), J. Am. Chem. Soc. 113, 6187-6196; Ichikawa, Y. et al. (1998), J. Am. Chem. Soc. 120, 3007-3018; Legler, G. et al. (1986), Carobydr. Res. 155, 119-129; Wong, C.-H. et al. (1995), Angew. Chem. Int. Ed. Engl. 34, 412-432; Wong, C.-H. et al. (1995), Angew. Chem. Int. Ed. Engl. 34, 521-546; Hughes, A. B. et al. (1994), Nat. Prod. Rep. 135-162; and Qian, X. et al. (2000), Glycosyltransferase inhibitors, In Carbohydrates in Chemistry and Biology, (Ernst, B., Hart, G. W. & Sinay, P., ed.) vol. 3, pp. 293-312, Wiley-VCH, Weinheim).